The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
With the rise in demand for green technologies, various efforts have been placed in developing systems and methods for redirecting sunlight to interiors of buildings. For example, “Project Summary Report—Daylight in Buildings”, published by the International Energy Agency in 2010; U.S. patent publication 2010/0254010 to Whitehead et al. titled “Adaptive Sunlight Redirector”, filed Jun. 16, 2008; U.S. patent publication 2012/0011782 to Kolas et al. titled “Fenestration System with Solar Cells”, filed Sep. 28, 2011; U.S. Pat. No. 8,027,092 to Huff et al. titled “Curved Light Shelf System for Daylighting an Interior Space”, filed Jan. 21, 2011; U.S. patent publication 2005/0128728 to Eisenman et al. titled “Light Tube System for Distributing Sunlight or Artificial Light Singly or in Combination”, filed Jan. 7, 2005; U.S. patent publication 2011/0272002 to Liu titled “Sunlight Collecting System for Illumination”, filed May 3, 2011; and U.S. patent publication 2006/0013001 to Roth titled “Reflectors for Condensed Light Beam Distribution”, filed Jul. 5, 2005 describe various systems that redirect available sunlight from a window, a roof or other location to the interior of a building.
Unfortunately, the above known references all exhibit certain limitations. For instance, the locations on which the light collecting/harvesting structures can be mounted appear to be limited to those that receive abundant sunlight throughout the day (e.g., the roof, the side(s) of the building that faces the sun). Furthermore, the usefulness of the available sunlight received by light collecting/harvesting structures, in terms of its ability to be efficiently introduced into and guided by the light guiding structure, varies throughout the day as the sunlight comes from different directions at different times of the day.
U.S. Pat. No. 8,611,011 to Whitehead teaches systems that overcome many of the limitations of systems that came before it, and enables sunlight to be redirected at a first angle and further distributed at a different angle to an interior of the building.
International Patent Application Publication WO2013/059908 to Whitehead describes the sunlight redirector shown in Prior Art FIG. 1, which includes a plurality of longitudinal, pivotable mirrors. The '908 Publication's sunlight redirector 10 includes a plurality of parallel, uniformly spaced, longitudinal mirror segments 12, which are interconnected in a manner similar to that used to interconnect Venetian blind slats. A controller coupled to one or more of segments 12 can be selectably actuated to simultaneously pivot all of segments 12, as indicated by double-headed arrow 14. Segments 12 can thus be pivotally adjusted, in the manner of a Venetian blind, such that their respective normal vectors 16 remain parallel. Segments 12 are of differing lengths, and are arranged such that sunlight redirector 10 has a circular front elevational shape. Sunlight redirector 10 is rotatable about its normal vector 18, as indicated by double-headed arrow 20.
Sunlight redirector 10 can thus be rotated to track the sun's azimuthal motion relative to the array's normal vector 18, and segments 12 can be pivotally adjusted to compensate for changes in the sun's altitude, so that light rays reflected by segments 12 will be redirected in a desired, fixed direction, e.g. parallel to normal vector 18 to facilitate redirection of light rays through a wall opening to illuminate the interior of a building.
Prior Art FIGS. 2A, 2B and 2C illustrate a potential disadvantage of using sunlight redirector 10's segments 12 to redirect light—redirection efficiency depends on the desired redirection angle. FIG. 2A depicts a small redirection angle situation in which the mirror segments (represented by solid lines 12) are nearly parallel to the incident light, so most rays (represented by dashed lines) do not strike the mirrors and are therefore not redirected as desired. FIG. 2B depicts an intermediate situation in which the mirror segments are obliquely angled relative to the incident light, with most rays striking the mirrors and being redirected as desired. FIG. 2C depicts a situation in which the desired redirection angle is so large that the mirror segments are positioned at such a large oblique angle relative to the incident light that most rays which strike the mirrors are redirected onto an adjacent mirror, then further redirected away from the desired direction. The FIGS. 2A and 2C scenarios are problematic since it is desirable to redirect rays corresponding to a wide range of sun angles. Another potential disadvantage of sunlight redirector 10 is possible increased complexity and cost in rotatably moving sunlight redirector 10 about normal vector 18.
Prior Art FIG. 3 depicts a stationary sunlight redirector 30 which attempts to overcome the potential disadvantages of the '908 Publication, which can be found in International Patent Application No. PCT/CA2014/000368. The '368 Application describes sunlight redirectors in which longitudinally outward segments 70A, 72A, 74A, 76A are adjustably positionable throughout a range of sun-tracking positions. Inward segments 70B, 72B, 74B, 76B, 78B either remain fixed in position at all times or they may be moved, twice per day, between the first and second fixed positions.
Unfortunately, while the approach of the '368 Application can be somewhat effective, the additional cost and complexity of providing adjustably positionable inward mirror segments 70A, 72A, 74A may not be warranted in all cases.
It has yet to be appreciated that a light distribution system could be highly effective and produced at a relatively low cost. Thus, there is still a need in the art for improved light distribution systems and methods.